Homescreen Improvements

Related to #614

Changed nav bar links into buttons. They have a custom button style to pair well with the logo.
Changed tutorials into buttons. Admittedly I did this because I misread an issue, but I think it looks good, and it does free up vertical space. These are probably going to change or go away anyway, so there's no point reverting my change.
Improved the ugly "Owner has not written a description" image